According to research published by IDC (late last year), quoted in an article from CNET.com, the world’s largest computer makers by market share are
1. Hewlett Packard
2. Acer
3. Dell
4. Lenovo
5. Toshiba

—
My 2 cents: always be sure to compare service, quality, and price. Just because one company sells the most computer does not mean they are the BEST!!